Concrete bridging beam form



Sept. 8,' 1964 J. C. WELCH CONCRETE BRIDGING BEAM FORM Filed March 20, 1959 United States Patent 3,147,571 CONCRETE BGING BEAM FGRM John C. Welsh, Shaker Heights, Uhio, assignor to Bethlehem Steel Company, a corporation of Pennsylvania Fiied Mar. 20, 1959, Ser. No. 800,672 4 Claims. (Cl. 50-291) This invention relates to metal concrete forms and more particularly to forms for constructing concrete bridging beams between adjacent steel joists or trusses.

A monolithic concrete floor or ceiling is commonly constructed by first fastening a corrugated metal decking to the top chord of metal joists. Then a thin concrete slab is poured on top of the metal decking. The slab and decking combination usually are not strong enough to distribute a heavy concentrated load to the joists. Therefore, various types of bridging beams have been developed that run transverse to the joists and help to distribute concentrated loads among several adjacent joists. The bridging beams also give lateral support to the metal joists to prevent the joists from tilting when subject to a heavy concentrated load. For effective load distribution, the bridging beams should be integrally bonded to the floor slab and also to the joists.

Bridging beams are frequently made of reinforced concrete since it is strong, and fireproof. Heretofore the pouring of such reinforced concrete bridging beams has been costly, time-consuming, and difficult because elaborate form work was required in order to fit the form closely around the web and chord members of the joists. Only a closely fitted form will prevent the fresh concrete from falling away from the joist members when it is poured. Thus a closely fitted form insures a good structural bond between the concrete of the bridging beam and the steel members of the joists. Some previous formwork arrangements also required the bridging beam to be poured and the concrete set before the floor slab could be poured. It was then difficult to secure a good structural bond between the bridging beam and the floor slab.

It is therefore an object of my invention to provide a metal beam form that fits closely around the joist members to permit effective pouring of the fresh concrete.

It is a further object of my invention to provide a metal beam form that permits the bridging beam and the floor slab to be poured at the same time.

It is a still further object of my invention to provide a metal beam form that can be easily, quickly, and inexpensively installed.

The foregoing objects and the means whereby they are attained will be more fully understood from the following description and claims together with the drawings in which FIGURE 1 is an isometric view partially in section of the metal beam forms in place between adjacent open web steel joists.

FIGURES 2 and 3 are elevation views of the metal beam forms to show the installation sequence.

Referring to FIGURE 1, joist 3 consists of top chord members 4, rod-shaped diagonal web members 5, and bottom chord members 6. A corrugated sheet metal decking 2 rests upon and is fastened to the top chord members 4. A concrete slab 1 is poured on top of the metal decking 2.

The bridging beam forms 7 are made of a relatively light gage metal sheet. The form 7 consists of a substantially U-shaped channel portion 8 with outwardly horizontally extending flanges 9. End 10 includes two notched bendable flaps 12 cut out from the channel portion 8. End 13 includes a cut out notch 14, and channel portion 8 is beveled downwardly toward end 10.

The installation procedure will be apparent by referring to FIGURES 1, 2 and 3. Joists 3 are first put in place 3,147,571 Patented Sept. 8, 1964 and the metal decking sheets 2 are fastened to the top chord members 4. A space equal to the width of form 7 is left between the metal decking sheets 2 at the points where a bridging beam is desired. The notched flaps 12 of end 10 are bent inwardly toward each other as shown in FIGURE 1. End 13 is tilted upwardly as shown in FIGURE 2 and flapped end 10 is inserted between the diagonal web members 5. The U-shaped channel portion 8 is thus supported by the diagonal web members 5 and the bottom chord members 6. End 13 is then lowered until it overlaps and rests in the channel portion 8 of a similarly installed identical adjacent form 15. End 13 is beveled as shown in FIGURE 2 so that it clears the top chord member 4 during this lowering procedure.

When form 7 is in a horizontal position, it is shifted longitudinally so that notch 14 abuts chord member 4. As soon as adjacent form 16 is in place, the notched flaps 12 are opened to closely surround chord members 4.

Flanges 9 rest upon the metal decking sheets 2 and can be fastened to the sheets 2 if so desired. In this manner a series of forms can be placed to make a continuous beam of any length.

After the forms are in place, ordinary reinforcing rods may be placed in them. Fresh concrete is then poured into the for-ms and on top of the decking, thus forming a monolithic slab and beam combination.

After the concrete has set, the forms may be either left in place or stripped. The relatively light gage and short sections permit easy handling and installation. The channel-like shape permits a quantity of these forms to be stacked one inside the other for shipment and storage on the construction site.

The length, width, and depth of the beam form are a function of the joist size and spacing and will vary accordingly. The notched portions of the form can be cut out to fit the wide variety of shapes used for chord members. The notches should be accurately cut in the shop so that a concrete tight seal is created when the flaps are opened around the chord members.

As many possible embodiments may be made of the invention without departing from the scope thereof, it is to be understood that all matter set forth or shown in the accompanying drawing is to be interpreted as illustrative and not in a limiting sense.

I claim:

1. A sheet metal beam form for concrete bridging beams or the like, said form comprising a substantially U-shaped channel with outwardly horizontally extending flanges, one end of said beam form being cut to form a pair of notched bendable flaps in the upper portion of the vertical side walls of the channel, each of said flaps being bendable about respective vertical axes, the other end of said beam form being cut to form a notched portion beveled downwardly towards said end having the bendable flaps.

2. In a steel joist and concrete slab structure a plu rality of overlapping sheet metal beam forms for concrete bridging beams or the like, said forms each comprising a substantially U-shaped channel with outwardly horizontally extending flanges, one end of each said beam form being slotted to form a pair of notched bendable flaps in the upper portion of the vertical side walls of the channel, each of said flaps being bendable about respective vertical axes, the other end of each said beam form cut to form a notched portion beveled downwardly towards said end having the bendable flaps.

3. In a steel joist, and concrete slab structure, a plurality of open-web steel joists, a plurality of overlapping sheet metal beam forms for concrete bridging the space between said joists, said forms each comprising a substantially U-shaped channel, the upper side walls of said channel being provided at one end with bendable notched flap portions, the notches of said flap portions being adapted to accommodate the upper chord members of said joists.

4. In a steel joist and concrete slab structure, a plurality of open-web steel joists, a plurality of overlapping sheet metal beam forms for concrete bridging the space between said joists, said forms each comprising a substantially U-shaped channel, the upper side walls of said channel being provided-at one end with two notched flap portions, each bendable about respective vertical axes, the notches of said flap portions being adapted to accommodate the upper chord member of a joist, the other end being provided with notched portions adapted to accommodate the upper chord member of an adjacent joist and with a portion beveled downwardly towards said end having the bendable fla-ps totacilitate installation.

References Cited in the file of this patent UNITED STATES PATENTS 

3. IN A STEEL JOIST, AND CONCRETE SLAB STRUCTURE, A PLURALITY OF OPEN-WEB STEEL JOISTS, A PLURALITY OF OVERLAPPING SHEET METAL BEAM FORMS FOR CONCRETE BRIDGING THE SPACE BETWEEN SAID JOISTS, SAID FORMS EACH COMPRISING A SUBSTANTIALLY U-SHAPED CHANNEL, THE UPPER SIDE WALLS OF SAID CHANNEL BEING PROVIDED AT ONE END WITH BENDABLE NOTCHED FLAP PORTIONS, THE NOTCHES OF SAID FLAP PORTIONS BEING ADAPTED TO ACCOMMODATE THE UPPER CHORD MEMBERS OF SAID JOISTS. 